Fuel compositions

ABSTRACT

The present invention is directed to the use of cyclic amide alkoxylate compounds as additives in fuel compositions having a major amount of a mixture of hydrocarbons in the gasoline boiling range and a minor amount of one or more cyclic amide alkoxylate compounds of the formula: ##STR1## wherein x is from 2 to 20 and y is from 1 to 50. R 1  and R 2  are independently hydrogen or hydrocarbyl of 1 to 100 carbon atoms. R 3  is hydrocarbyl of 1 to 100 carbon atoms and R 4  is independently hydrocarbyl of 2 to 100 carbon atoms. R 5  is hydrogen, hydrocarbyl of 1 to 100 carbon atoms or acyl of 1 to 20 carbon atoms. 
     The invention is also directed to the use of these cyclic amide alkoxylate compounds for decreasing intake valve deposits, controlling octane requirement increases and reducing octane requirement. The invention is further directed to novel cyclic amide alkoxylate compounds.

This is a continuation of application Ser. No. 08/303/116, filed Sep. 8, 1994, now abandoned, which is a continuation of Ser. No. 08/040,245 filed Mar. 30, 1993, now U.S. Pat. No. 5,352,251.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the use of cyclic amide alkoxylate compounds as additives in fuel compositions and the use of these compounds to decrease intake valve deposits, control octane requirement increase, and reduce octane requirement. The present invention further relates to a novel class of cyclic amide alkoxylate compounds.

2. Background

The octane requirement increase effect exhibited by internal combustion engines, e.g., spark ignition engines, is well known in the art. This effect may be described as the tendency for an initially new or relatively clean engine to require higher octane quality fuel as operating time accumulates, and is coincidental with the formation of deposits in the region of the combustion chamber of the engine.

During the initial operation of a new or clean engine, a gradual increase in octane requirement, i.e., fuel octane number required for knock-free operation, is observed with an increasing build up of combustion chamber deposits until a stable or equilibrium octane requirement level is reached. This level appears to correspond to a point in time when the quantity of deposit accumulation on the combustion chamber and valve surfaces no longer increases but remains relatively constant. This so-called "equilibrium value" is normally reached between 3,000 and 20,000 miles or corresponding hours of operation. The actual equilibrium value of this increase can vary with engine design and even with individual engines of the same design; however, in almost all cases, the increase appears to be significant, with octane requirement increase values ranging from about 2 to about 10 research octane numbers being commonly observed in modern engines.

The accumulation of deposits on the intake valves of internal combustion engines also presents problems. The accumulation of such deposits is characterized by overall poor driveability including hard starting, stalls, and stumbles during acceleration and rough engine idle.

Many additives are known which can be added to hydrocarbon fuels to prevent or reduce deposit formation, or remove or modify formed deposits, in the combustion chamber and on adjacent surfaces such as intake valves, ports, and spark plugs, which in turn causes a decrease in octane requirement.

Continued improvements in the design of internal combustion engines, e.g., fuel injection and carburetor engines, bring changes to the environment of such engines thereby creating a continuing need for new additives to control the problem of inlet system deposits and to improve driveability which is usually related to deposits.

It would be an advantage to have fuel compositions which would reduce the formation of deposits and modify existing deposits that are related to octane requirement increase and poor driveability in modern engines which burn hydrocarbon fuels.

SUMMARY OF THE INVENTION

The present invention is directed to the use of cyclic amide alkoxylate compounds as additives in fuel compositions comprising a major amount of a mixture of hydrocarbons in the gasoline boiling range and a minor amount of one or more cyclic amide alkoxylate compounds of the formula: ##STR2## wherein x is from 2 to 20 and y is from 1 to 50. R₁ and R₂ are independently hydrogen or hydrocarbyl of 1 to 100 carbon atoms. R₃ is hydrocarbyl of 1 to 100 carbon atoms and R₄ is independently hydrocarbyl of 2 to 100 carbon atoms. R₅ is hydrogen, hydrocarbyl of 1 to 100 carbon atoms or acyl of 1 to 20 carbon atoms.

The invention is also directed to the use of these cyclic amide alkoxylate compounds for decreasing intake valve deposits, controlling octane requirement increases and reducing octane requirement.

The invention is further directed to novel cyclic amide alkoxylate compounds of the formula: ##STR3## wherein x is from 2 to 4 and y is from 1 to 50. In such novel compounds, R₁ and R₂ are independently hydrogen or hydrocarbyl of 1 to 100 carbon atoms, R₃ is hydrocarbyl of 1 to 100 carbon atoms and R₄ is hydrocarbyl of 2 to 100 carbon atoms with the proviso that when y is greater than 1, each R₄ may be the same or different but at least R₃ or one R₄ must have at least four carbon atoms and R₅ is hydrogen, hydrocarbyl of 1 to 100 carbon atoms or acyl of 1 to 20 carbon atoms.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Compounds

The compounds of the present invention, broadly expressed as cyclic amide alkoxylates, are a new class of additives useful for hydrocarbon fuels, e.g., fuels in the gasoline boiling range, for preventing deposits in engines, controlling octane requirement increases and reducing octane requirement, while also decomposing during combustion to environmentally acceptable products. The compounds produce very little residue and are miscible with carriers and other detergents. Non-limiting illustrative embodiments of the compounds useful as additives in the instant invention include those of Formula I: ##STR4##

In Formula I, R₁ and R₂ are independently hydrogen or hydrocarbyl of 1 to 100 carbon atoms. Preferably, at least one of R₁ and R₂ is hydrogen. It is even more preferable if both R₁ and R₂ are hydrogen. As used herein, the term "hydrocarbyl" represents a radical formed by the removal of one or more hydrogen atoms from a carbon atom of a hydrocarbon (not necessarily the same carbon atom). Useful hydrocarbyls are aliphatic, aromatic, substituted, unsubstituted, acyclic or cyclic. Preferably, the hydrocarbyls are aryl, alkyl, alkenyl or cycloalkyl and are straight-chain or branched-chain. Representative hydrocarbyls include methyl, ethyl, butyl, pentyl, methylpentyl, hexenyl, ethylhexyl, dimethylhexyl, octamethylene, octenylene, cyclooctylene, methylcyclooctylene, dimethylcyclooctyl, isooctyl, dodecyl, hexadecenyl, octyl, eicosyl, hexacosyl, triacontyl and phenylethyl. When the hydrocarbyl is substituted, it contains a functional group such as carbonyl, carboxyl, nitro, amino, hydroxy (e.g. hydroxyethyl), oxyo, cyano, sulfonyl, and sulfoxyl. The majority of the atoms, other than hydrogen, in substituted hydrocarbyls are carbon, with the heteroatoms (i.e., oxygen, nitrogen, sulfur) representing only a minority, 33% or less, of the total non-hydrogen atoms present.

When R₁ and/or R₂ are hydrocarbyl, they are each preferably hydrocarbyl of 1 to 20 carbon atoms, even more preferably, alkyl of 1 to 20 carbon atoms and most preferably alkyl of 1 to 8 carbon atoms. When R₁ and/or R₂ are hydrocarbyl of a relatively high number of carbon atoms, i.e., greater than about 50 carbon atoms, R₁ and/or R₂ will be represented by polymeric hydrocarbyls such as polyisobutylene, polybutene, polypropylene or polyalpha olefin.

In Formula I, x is from 2 to 20, preferably from 3 to 11. Particularly preferred compounds of Formula I are those in which x is 3, 5 or 11, and especially those compounds in which x is 3.

R₃ is hydrocarbyl, as defined hereinbefore, of 1 to 100 carbon atoms, preferably of 1 to 20 carbon atoms. When R₃ is hydrocarbyl of a relatively high number of carbon atoms, i.e., greater than about 50 carbon atoms, R₃ will be represented by polymeric hydrocarbyls such as polyisobutylene, polybutene, polypropylene or polyalpha olefin. Particularity preferred compounds are those in which R₃ is alkyl of 1 to 20 carbon atoms, more preferably when R₃ is alkyl of 2 to 10 carbon atoms, and most preferably alkyl of 2 or 4 carbon atoms.

In Formula I, y is from 1 to 50, preferably from 8 to 40, and even more preferably from 18 to 24. Those of ordinary skill in the art will recognize that when the compounds of Formula I are utilized in a composition, y will not have a fixed value but will instead be represented by a range of different values. As used in this specification, y is considered to be a (number) average of the various values of y that are found in a given composition, which number has been rounded to the nearest integer. This is indicated in the various examples by the polydispersity (polydispersity=molecular weight based on the weight average divided by the molecular weight based on the number average).

Each R₄ is independently hydrocarbyl, as defined hereinbefore, of 2 to 100 carbon atoms, preferably of 2 to 20 carbon atoms, more preferably of 2 to 14 carbon atoms and most preferably four carbon atoms. When R₄ is hydrocarbyl of a relatively high number of carbon atoms, i.e., greater than about 50 carbon atoms, R₄ will be represented by polymeric hydrocarbyls such as polyisobutylene, polybutene, polypropylene or polyalpha olefin.

Particularly preferred compounds of Formula I are those in which R₄ is hydrocarbyl (geminal or vicinal) of the formula: ##STR5## wherein R₆, R₇ and R₈ are each independently hydrogen or hydrocarbyl, as defined hereinbefore, of 1 to 98 carbon atoms. Preferred R₆, R₇ and R₈ groups are hydrogen or hydrocarbyl, as defined hereinbefore, of 1 to 18 carbon atoms. R₇ and R₆, or alternatively R₆ and R₈, may be taken together to form a divalent linking hydrocarbyl group of 3 to 12 carbon atoms.

The most preferred compounds of Formula I are those in which R₄ is hydrocarbyl as represented by Formula III above wherein R₈ is hydrogen and R₆ is independently hydrogen, alkyl of 1 to 18 carbon atoms or oxy-substituted hydrocarbyl of 1 to 18 carbon atoms, particularly those compounds where R₈ is hydrogen and R₆ is independently hydrogen or alkyl of 1 to 2 carbon atoms, especially those compounds where R₈ is hydrogen and R₆ is alkyl of two carbon atoms.

When R₆ is oxy-substituted hydrocarbyl of 1 to 18 carbon atoms, R₆ is preferably an alkoxy-substituted alkylene of 1 to 18 carbon atoms or an aryloxy-substituted alkylene of 1 to 18 carbon atoms. Particularly preferred alkoxy-substituted alkylene groups include ethylhexyleneoxymethylene, isopropoxymethylene, butoxymethylene and mixtures thereof. Particularly preferred aryl-substituted alkylene groups include nonylphenoxymethylene, phenoxymethylene and mixtures thereof.

When y is greater than 1, the individual R₄ 's are the same or different. For example, if y is 20, each R₄ can be alkyl of four carbon atoms. Alternatively, the R₄ 'S can differ and for instance, independently be alkyl from two to four carbon atoms. When the R₄ 's differ, they may be present in blocks, i.e., all y groups in which R₄ is alkyl of three carbon atoms will be adjacent, followed by all y groups in which R₄ is alkyl of two carbon atoms, followed by all y groups in which R₄ is alkyl of four carbon atoms. When the R₄ 's differ, they may also be present in any random distribution.

R₅ is hydrogen, hydrocarbyl, as defined hereinbefore, of 1 to 100 carbon atoms or acyl of 1 to 20 carbon atoms. Preferably, R₅ is hydrogen. When R₅ is hydrocarbyl, it is preferably of 1 to 70 carbon atoms, more preferably of 1 to 20 carbon atoms. The term "acyl", as used herein, represents the residue of an organic acid in which the --OH of a carboxyl group is removed to form R₉ CO--. R₉ is monovalent hydrocarbyl, as defined hereinbefore, of 2 to 19 carbon atoms, preferably, alkyl or aryl of 2 to 19 carbon atoms. Representative acyl groups include acetyl-, butyryl-, caproyl-, acrylyl-, benzoyl- and methacrylyl-. Substituted acyl groups are also contemplated. Substituted acyl groups contain a functional group such as hydroxy, cyano, nitro and the substituents of the hydrocarbyl groups as defined hereinbefore.

Of the compounds of Formula I, the following class of compounds are novel and are defined by the following formula: ##STR6## wherein x is from 2 to 4, preferably in which x is 3. R₁, R₂, R₃, R₄ and y are as defined hereinbefore with the proviso that when y is greater than 1, at least R₃ or one R₄ must have at least four carbon atoms. R₅ is as defined hereinbefore.

The compounds of Formula I have a total weight average molecular weight of at least 600. Preferably, the total weight average molecular weight is from about 800 to about 4000, even more preferably from about 1000 to about 2000.

Typical compounds represented by Formula I include those listed by structure in Table 1:

                                      TABLE 1                                      __________________________________________________________________________     For purposes of clarity the hydrogens have been                                eliminated from the ring structures of Table 1 and the standard                schematic structure for a benzene ring (without hydrogen and                   carbon atoms) has been used.                                                   __________________________________________________________________________      ##STR7##                                                                      wherein y is from 18 to 24 and Z is independently H, CH.sub.3 or               CH.sub.2 CH.sub.3 including mixtures thereof.                                   ##STR8##                                                                      wherein y is from 18 to 24 and Z is independently H, CH.sub.3 or               CH.sub.2 CH.sub.3 including mixtures thereof.                                   ##STR9##                                                                      wherein y is from 8 to 40.                                                      ##STR10##                                                                     wherein y is from 8 to 40.                                                      ##STR11##                                                                     wherein the sum of y and y' is from 1 to 50.                                    ##STR12##                                                                     wherein y is from 8 to 40.                                                     __________________________________________________________________________

The compounds of Formula I are illustratively prepared by alkoxylation, i.e., reacting an initiator selected from cyclic amidoalcohols or cyclic amides with one or more epoxides in the presence of a potassium compound.

In one embodiment, the compounds of Formula I are prepared utilizing cyclic amidoalcohol initiators represented by the general formula: ##STR13## wherein R₁, R₂, R₃ and x have the above meanings. Non-limiting examples of cyclic amidoalcohol initiators which are employed include N-(2-hydroxyethyl)-pyrrolidinone, N- 2-(2-hydroxyethoxy)ethyl!-pyrrolidinone, N-(2-hydroxypropyl)-pyrrolidinone and N-(2-hydroxy-2-methyl-ethyl)-pyrrolidinone, with N-(2-hydroxyethyl)-pyrrolidinone being the most preferred.

Select cyclic amidoalcohol initiators are available commercially, such as, N-(2-hydroxyethyl)-pyrrolidinone (obtained from International Specialty Products or Aldrich Chemical Company). The cyclic amidoalcohol initiators are also prepared by any of the methods known and described in the art, for example by the method of Puetzer et al in J. Am. Chem. Soc. 74 4959 (1952), by reacting a lactone of the formula: ##STR14## with an aminoalcohol of the formula:

    NH.sub.2 --R.sub.3 --OH                                    (VII)

wherein R₁, R₂, R₃ and x have the above meanings. Illustrative lactones for use in making the cyclic amidoalcohols include: α-methyl-γ-butyrolactone, β-methyl-γ-butyrolactone, ε-caprolactone, γ-caprolactone, γ-phenyl-γ-butyrolactone, phthalide, 3,3a,6,6a-tetrahydro-2H-cyclopenta b!furan-2-one, tetronic acid (tetrahydrofuran-2,6-dione), β-propiolactone and isochromanone. Illustrative aminoalcohols for reacting with lactones to make the cyclic amidoalcohol initiators include: 2-amino-1-butanol, 2-(2-aminoethoxy) ethanol, 2-amino-2-ethyl-1,3-propanediol, 2-amino-2-methyl-1-propanol, 3-amino-1-propanol and 1-amino-2-propanol.

In an alternative embodiment, the compounds of Formula I are prepared by reacting with epoxide the cyclic amide initiators of the general formula: ##STR15## wherein R₁, R₂ and x have the above meanings. Non-limiting examples of cyclic amides which can be employed include cycloalkyl lactams such as, cyclopropyl lactam, cyclobutyl lactam (butyrolactam), cyclopentyl lactam, cyclohexyl lactam (caprolactam), cycloheptyl lactam and cyclooctyl lactam, with cyclopropyl lactam, cyclobutyl lactam and cyclohexyl lactam being the most preferred.

Select cyclic amide initiators are also available commercially, such as, ε-caprolactam (ε-hexanolactam available commercially from Aldrich Chemical Company), 2-pyrrolidinone (pyrrolidone or γ-butyrolactam available commercially from Aldrich Chemical Company) and laurallactam (2-azacyclotridecanone available commercially from Aldrich Chemical Company) with ε-caprolactam being the most preferred.

The one or more epoxides employed in the reaction with the initiators to prepare the compounds of Formula I contain from 2 to 100 carbon atoms, preferably from 2 to 20 carbon atoms, more preferably from 2 to 14 carbon atoms, and most preferably four carbon atoms. The epoxides may be internal epoxides such as 2,3 epoxides of the formula: ##STR16## wherein R₆ and R₇ have the above meanings or terminal epoxides such as 1,2 epoxides of the formula: ##STR17## wherein R₆ and R₈ have the above meanings. In both Formulas IX and X, R₇ and R₆, or alternatively R₆ and R₈, may be taken together to form a cycloalkylene epoxide or a vinylidene epoxide by forming a divalent linking hydrocarbyl group of 3 to 12 carbon atoms.

When R₆, R₇ and/or R₈ are oxy-substituted hydrocarbyl, suitable compounds of Formulas IX and X will include compounds such as nonylphenyl glycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether, butyl glycidyl ether, alkyl C₁₂ -C₁₃ glycidyl ether, alkyl C₈ -C₁₀ glycidyl ether, 2-ethylhexyl glycidyl ether and isopropyl glycidyl ether.

In the preferred embodiment, the terminal epoxides represented by Formula X are utilized to form amido derivatives. Ideally these terminal epoxides are 1,2-epoxyalkanes. Suitable 1,2-epoxyalkanes include 1,2-epoxyethane, 1,2-epoxypropane, 1,2-epoxybutane, 1,2-epoxydecane, 1,2-epoxydodecane, 1,2-epoxyhexadecane, 1,2-epoxyoctadecane and mixtures thereof.

In a typical preparation of Formula I compounds, the one or more epoxides and initiator are contacted at a ratio from about 7:1 to about 55:1 moles of epoxide per mole of initiator. Preferably, they are contacted at a molar ratio from about 10:1 to about 30:1, with the most preferred molar ratio being about 20:1.

The reaction is carried out in the presence of potassium compounds which act as alkoxylation catalysts. Such catalysts are conventional and include potassium methoxide, potassium ethoxide, potassium hydroxide, potassium hydride and potassium-t-butoxide. The preferred catalysts are potassium hydroxide and potassium-t-butoxide. The catalysts are used in a base stable solvent such as alcohol, ether or hydrocarbons. The catalysts are employed in a wide variety of concentrations. Generally, the potassium compounds will be used in an amount from about 0.02% to about 5.0% of the total weight of the mixture, preferably from about 0.1% to about 2.0% of the total weight of the mixture, and most preferably about 0.2% of the total weight of the mixture.

The reaction is conveniently carried out in a conventional autoclave reactor equipped with heating and cooling means. The process is practiced batchwise, continuously or semicontinuously.

The manner in which the alkoxylation reaction is conducted is not critical to the invention. Illustratively, the initiator and potassium compound are mixed and heated under vacuum for a period of at least 30 minutes. The one or more epoxides are then added to the resulting mixture, the reactor sealed and pressurized with nitrogen, and the mixture stirred while the temperature is gradually increased.

The temperature for alkoxylation is from about 80° C. to about 250° C., preferably from about 100° C. to about 150° C., and even more preferably from about 120° C. to about 140° C. The alkoxylation reaction time is generally from about 2 to about 20 hours, although longer or shorter times are employed.

Alkoxylation processes of the above type are known and are described, for example in U.S. Pat. No. 4,973,414, U.S. Pat. No. 4,883,826, U.S. Pat. No. 5,123,932 and U.S. Pat. No. 4,612,335, each incorporated herein by reference.

The product of Formula I is normally liquid and is recovered by conventional techniques such as filtration and distillation. The product is used in its crude state or is purified, if desired, by conventional techniques such as aqueous extraction, solid absorption and/or vacuum distillation to remove any remaining impurities.

Other methods for making the compounds of Formula I are known by those skilled in the art. For example, the compounds of Formula I are prepared by reacting an initiator as described hereinbefore with other cyclic ethers. In addition, other catalyst chemistry, such as the use of acidic catalysts, can be employed to achieve the compounds of Formula I.

Fuel Compositions

The compounds of Formula I are useful as additives in fuel compositions which are burned or combusted in internal combustion engines. The fuel compositions of the present invention comprise a major amount of a mixture of hydrocarbons in the gasoline boiling range and a minor amount of one or more of the compounds of Formula I. As used herein, the term "minor amount" means less than about 10% by weight of the total fuel composition, preferably less than about 1% by weight of the total fuel composition and more preferably less than about 0.1% by weight of the total fuel composition.

Suitable liquid hydrocarbon fuels of the gasoline boiling range are mixtures of hydrocarbons having a boiling range of from about 25° C. to about 232° C., and comprise mixtures of saturated hydrocarbons, olefinic hydrocarbons and aromatic hydrocarbons. Preferred are gasoline mixtures having a saturated hydrocarbon content ranging from about 40% to about 80% by volume, an olefinic hydrocarbon content from 0% to about 30% by volume and an aromatic hydrocarbon content from about 10% to about 60% by volume. The base fuel is derived from straight run gasoline, polymer gasoline, natural gasoline, dimer and trimerized olefins, synthetically produced aromatic hydrocarbon mixtures, or from catalytically cracked or thermally cracked petroleum stocks, and mixtures of these. The hydrocarbon composition and octane level of the base fuel are not critical. The octane level, (R+M)/2, will generally be above about 85.

Any conventional motor fuel base can be employed in the practice of the present invention. For example, hydrocarbons in the gasoline can be replaced by up to a substantial amount of conventional alcohols or ethers, conventionally known for use in fuels. The base fuels are desirably substantially free of water since water could impede a smooth combustion.

Normally, the hydrocarbon fuel mixtures to which the invention is applied are substantially lead-free, but may contain minor amounts of blending agents such as methanol, ethanol, ethyl tertiary butyl ether, methyl tertiary butyl ether, and the like, at from about 0.1% by volume to about 15% by volume of the base fuel, although larger amounts may be utilized. The fuels can also contain conventional additives including antioxidants such as phenolics, e.g., 2,6-di-tert-butylphenol or phenylenediamines, e.g., N,N'-di-sec-butyl-p-phenylenediamine, dyes, metal deactivators, dehazers such as polyester-type ethoxylated alkylphenol-formaldehyde resins. Corrosion inhibitors, such as a polyhydric alcohol ester of a succinic acid derivative having on at least one of its alpha-carbon atoms an unsubstituted or substituted aliphatic hydrocarbon group having from 20 to 500 carbon atoms, for example, pentaerythritol diester of polyisobutylene-substituted succinic acid, the polyisobutylene group having an average molecular weight of about 950, in an amount from about 1 ppm by weight to about 1000 ppm by weight, may also be present. The fuels can also contain antiknock compounds such as methyl cyclopentadienylmanganese tricarbonyl and ortho-azidophenol as well as co-antiknock compounds such as benzoyl acetone.

An effective amount of one or more compounds of Formula I are introduced into the combustion zone of the engine in a variety of ways to prevent build-up of deposits, or to accomplish the reduction of intake valve deposits or the modification of existing deposits that are related to octane requirement. As mentioned, a preferred method is to add a minor amount of one or more compounds of Formula I to the fuel. For example, one or more compounds of Formula I are added directly to the fuel or are blended with one or more carriers and/or one or more additional detergents before being added to the fuel.

The amount of cyclic amidoalcohol alkoxylates used will depend on the particular variation of Formula I used, the engine, the fuel, and the presence or absence of carriers and additional detergents. Generally, each compound of Formula I is added in an amount up to about 1000 ppm by weight, especially from about 1 ppm by weight to about 600 ppm by weight based on the total weight of the fuel composition. Preferably, the amount will be from about 50 ppm by weight to about 400 ppm by weight, and even more preferably from about 75 ppm by weight to about 250 ppm by weight based on the total weight of the fuel composition.

The carrier, when utilized, will have a weight average molecular weight from about 500 to about 5000. Suitable carriers, when utilized, include hydrocarbon based materials such as polyisobutylenes (PIB's), polypropylenes (PP's) and polyalphaolefins (PAO's); polyether based materials such as polybutylene oxides (poly BO's), polypropylene oxides (poly PO's), polyhexadecene oxides (poly HO's) and mixtures thereof (i.e., both (poly BO)+(poly PO) and (poly--BO--PO)); and mineral oils such as Exxon Naphthenic 900 sus and high viscosity index (HVI) oils. The carrier is preferably selected from PIB's, poly BO's, and poly PO's, with poly BO's being the most preferred.

The carrier concentration in the final fuel composition is up to about 1000 ppm by weight. When a carrier is present, the preferred concentration is from about 50 ppm by weight to about 400 ppm by weight, based on the total weight of the fuel composition. Once the carrier is blended with one or more compounds of Formula I, the blend is added directly to the fuel or packaged for future use.

The fuel compositions of the present invention may also contain one or more additional detergents. When additional detergents are utilized, the fuel composition will comprise a mixture of a major amount of hydrocarbons in the gasoline boiling range as described hereinbefore, a minor amount of one or more compounds of Formula I as described hereinbefore and a minor amount of an additional detergent selected from polyalkenyl amines, Mannich amines, polyalkenyl succinimides, poly(oxyalkylene) carbamates, poly(alkenyl)-N-substituted carbamates and mixtures thereof. As noted above, a carrier as described hereinbefore may also be included. As used herein, the term "minor amount" means less than about 10% by weight of the total fuel composition, preferably less than about 1% by weight of the total fuel composition and more preferably less than about 0.1% by weight of the total fuel composition.

The polyalkenyl amine detergents utilized comprise at least one monovalent hydrocarbon group having at least 50 carbon atoms and at least one monovalent hydrocarbon group having at most five carbon atoms bound directly to separate nitrogen atoms of a diamine. Preferred polyalkenyl amines are polyisobutenyl amines. Polyisobutenyl amines are known in the art and representative examples are disclosed in various U.S. Patents including U.S. Pat. No. 3,753,670, U.S. Pat. No. 3,756,793, U.S. Pat. No. 3,574,576 and U.S. Pat. No. 3,438,757, each incorporated herein by reference. Particularly preferred polyisobutenyl amines for use in the present fuel composition include N-polyisobutenyl-N',N'-dimethyl-1,3-diaminopropane (PIB-DAP) and OGA-472 (a polyisobutenyl ethylene diamine available commercially from Oronite).

The Mannich amine detergents utilized comprise a condensation product of a high molecular weight alkyl-substituted hydroxyaromatic compound, an amine which contains an amino group having at least one active hydrogen atom (preferably a polyamine), and an aldehyde. Such Mannich amines are known in the art and are disclosed in U.S. Pat. No. 4,231,759, incorporated herein by reference. Preferably, the Mannich amine is an alkyl substituted Mannich amine.

The polyalkenyl succinmide detergents comprise the reaction product of a dibasic acid anhydride with either a polyoxyalkylene diamine, a hydrocarbyl polyamine or mixtures of both. Typically the succinmide is substituted with the polyalkenyl group but the polyalkenyl group may be found on the polyoxyalkylene diamine or the hydrocarbyl polyamine. polyalkenyl succinimides are also known in the art and representative examples are disclosed in various U.S. Patents including U.S. Pat. No. 4,810,261, U.S. Pat. No. 4,852,993, U.S. Pat. No. 4,968,321, U.S. Pat. No. 4,985,047, U.S. Pat. No. 5,061,291 and U.S. Pat. No. 5,147,414, each incorporated herein by reference.

The poly(oxyalkylene) carbamate detergents comprise an amine moiety and a poly(oxyalkylene) moiety linked together through a carbamate linkage, i.e.,

    --O--C(O)--N--                                             (XI)

These poly(oxyalkylene) carbamates are known in the art and representative examples are disclosed in various U.S. Patents including, U.S. Pat. No. 4,191,537, U.S. Pat. No. 4,160,648, U.S. Pat. No. 4,236,020, U.S. Pat. No. 4,270,930, U.S. Pat. No. 4,288,612 and U.S. Pat. No. 4,881,945, each incorporated herein by reference. Particularly preferred poly(oxyalkylene) carbamates for use in the present fuel composition include OGA-480 (a poly(oxyalkylene) carbamate which is available commercially from Oronite).

The poly(alkenyl)-N-substituted carbamate detergents utilized are of the formula: ##STR18## in which R is a poly(alkenyl) chain; R¹ is a hydrocarbyl or substituted hydrocarbyl group; and A is an N-substituted amino group. Poly(alkenyl)-N-substituted carbamates are known in the art and are disclosed in U.S. Pat. No. 4,936,868, incorporated herein by reference.

The one or more additional detergents are added directly to the hydrocarbons, blended with one or more carriers, blended with one or more compounds of Formula I, or blended with one or more compounds of Formula I and one or more carriers before being added to the hydrocarbons.

The concentration of the one or more additional detergents in the final fuel composition is generally up to about 1000 ppm by weight for each additional detergent. When one or more additional detergents are utilized, the preferred concentration for each additional detergent is from about 50 ppm by weight to about 400 ppm by weight, based on the total weight of the fuel composition, even more preferably from about 75 ppm by weight to about 250 ppm by weight, based on the total weight of the fuel composition.

ENGINE TESTS Decreasing Intake Valve Deposits

The invention further provides a process for decreasing intake valve deposits in engines utilizing the cyclic amide alkoxylates of the present invention. The process comprises supplying to and combusting or burning in an internal combustion engine a fuel composition comprising a major amount of hydrocarbons in the gasoline boiling range and a minor amount of one or more compounds of Formula I as described hereinbefore.

By supplying to and combusting or burning the fuel composition in an internal combustion engine, deposits in the induction system, particularly deposits on the tulips of the intake valves, are reduced. The reduction is determined by running an engine with clean induction system components and pre-weighed intake valves on dynamometer test stands in such a way as to simulate road operation using a variety of cycles at varying speeds while carefully controlling specific operating parameters. The tests are run for a specific period of time on the fuel composition to be tested. Upon completion of the test, the induction system deposits are visually rated, the valves are reweighed and the weight of the valve deposits is determined.

Controlling Octane Requirement Increases

The invention further provides a process for controlling octane requirement increases in engines utilizing the cyclic amide alkoxylates of the present invention. The process comprises supplying to and combusting or burning in an internal combustion engine a fuel composition comprising a major amount of hydrocarbons in the gasoline boiling range and a minor amount of one or more compounds of Formula I as described hereinbefore.

Octane requirement is the maximum octane number of a gasoline that presents trace knock in a given engine within the engine's normal operating range. An increase in octane requirement is generally experienced during mileage accumulation on a new engine. The increase is typically attributed to an increase in engine deposits. Octane requirement increase control is a performance feature that is usually expressed as a comparison of the octane requirement increase developed with a gasoline containing additives (test gasoline) relative to a version of the same gasoline without additives (base gasoline), i.e., the positive difference obtained by subtracting the results of gasoline containing additives from gasoline which does not contain additives.

The test protocol for octane requirement increase control must establish the stable octane requirement of the base gasoline relative to a clean engine. Base gasoline is typically the test gasoline without additives or special treatment; however, it may be gasoline containing additives for a specific comparison.

Octane requirement increase control testing consists of operating an engine assembled with clean combustion chambers and induction system components on a test gasoline to octane stabilization, measuring the octane requirement at regular intervals. The octane requirement increase control is the difference between the stabilized octane requirement of the engine operated on test gasoline and that of the stabilized octane requirement of the engine on base gasoline.

Reduction of Octane Requirement

The invention still further provides a process for reducing octane requirement in engines utilizing the cyclic amide alkoxylates of the present invention. The process comprises supplying to and combusting or burning in an internal combustion engine a fuel composition comprising a major amount of hydrocarbons in the gasoline boiling range and a minor amount of one or more compounds of Formula I as described hereinbefore.

Octane requirement reduction is the reduction of the octane requirement of an engine by the action of a particular gasoline, usually measured as a decrease from a stabilized octane requirement condition.

Octane requirement reduction is a performance feature that demonstrates a reduction from the established octane requirement of a base gasoline in a given engine. Octane requirement reduction testing consists of operating an engine, which has achieved stable octane requirement using base gasoline, on a test gasoline for approximately 100 hours. Octane measurements are made daily and octane requirement reduction is a reduction of octane requirement from that of base gasoline. Several octane requirement reduction tests may be conducted in a series for fuel to fuel comparison, or test fuel to base fuel comparison, by restabilizing on base fuel between octane requirement reduction tests.

The contribution of specific deposits is determined by removing deposits of interest and remeasuring octane requirement immediately after the engine is warmed to operating temperature. The octane requirement contribution of the deposit is the difference in ratings before and after deposit removal.

The ranges and limitations provided in the instant specification and claims are those which are believed to particularly point out and distinctly claim the instant invention. It is, however, understood that other ranges and limitations that perform substantially the same function in substantially the same way to obtain the same or substantially the same result are intended to be within the scope of the instant invention as defined by the instant specification and claims.

The invention will be described by the following examples which are provided for illustrative purposes and are not to be construed as limiting the invention.

EXAMPLES COMPOUND PREPARATION

The cyclic amide alkoxylates used in the following examples were prepared by reacting an initiator with one or more epoxides in the presence of a potassium compound to produce compounds of Formula I (or Formula II) having a weight average molecular weight from about 600 to about 4000 as measured by gel permeation chromatography (GPC), nuclear magnetic resonance (NMR), infrared spectroscopy (IR), elemental analysis or nitrogen/amine analysis.

Example 1

A mixture of N-(2-hydroxyethyl)-pyrrolidinone (52 g, 0.40 moles), potassium hydroxide (1.9 g in 1.5 g water) and toluene (200 g) was heated to approximately 80° C. under reduced pressure of 10 mm Hg for over 30 minutes. The mixture was added along with 1,2-epoxybutane (598 g, 8.3 moles) to a one liter autoclave equipped with heating and cooling means. The autoclave was sealed and purged of air by pressurizing and depressurizing with nitrogen at 50 psi several times. With stirring and an initial nitrogen pressure of 50 psi, the mixture was heated slowly to 120° C. and held at this temperature for over 12 hours. During the process, a maximum autogenous pressure at 125 psi at 127° C. was observed. The pressure had dropped to 63 psi by the end of the reaction. The mixture was then cooled to ambient temperature, excess gas was vented and the product was recovered as a light brown liquid. This crude product was rotovapped at 80° C. and 10 mm Hg to remove light material. Approximately 1.0 g of 1,2-epoxybutane was removed, indicating nearly quantitative conversion of the 1,2-epoxybutane.

GPC, NMR and IR analysis were consistent with the desired structure of a N-(2-hydroxyethyl)-pyrrolidinone butoxylate at approximately 20 units of 1,2-epoxybutane adduct.

The crude product was further purified using an extraction procedure to remove trace amounts of color body. The crude product was dissolved in hexane (50% basis of product) and extracted utilizing water three times at ambient temperature. The organic layer was then subjected to rotovap at 80° C. and 10 mm Hg to obtain a final product having an estimated molecular weight of approximately 1600. GPC analysis indicated an average molecular weight of Mw=1250 and a polydispersity of 1.08.

Example 2

The procedure of Example 1 was repeated with the following exceptions: a mixture of N-(2-hydroxyethyl)-pyrrolidinone (48 g, 0.37 moles) and potassium hydroxide (1.7 g in 1.7 g water) was utilized in the absence of toluene. The mixture was added along with a mixture of 1,2-epoxybutane (442 g, 6.1 moles) and nonylphenol epoxide (110 g, 0.40 moles, an epoxy marketed as HELOXY 64 by Rhone-Poulene, with a structure derived from nonylphenol and epichlorohydrin) to the autoclave. The mixture was heated slowly to 118° C. and maintained at this temperature for over 8 hours.

The product was confirmed by GPC, NMR and IR analysis. The crude product was further purified by the procedure of Example 1 to give a final product having an estimated molecular weight of approximately 1600. GPC analysis indicated an average molecular weight of Mw=1100 and a polydispersity of 1.12.

Example 3

The procedure of Example 1 was repeated with the following exceptions: a mixture of N-(2-hydroxyethyl)-pyrrolidinone (HEP) (43.3 g, 0.34 moles) and potassium hydroxide (1.7 g in 1.7 g water) was utilized in the absence of toluene. The resulting mixture was added along with propylene oxide (498 g, 8.6 moles) to the autoclave. The mixture was heated slowly to from 117° C. to 120° C. and maintained at this temperature for over 6 hours.

NMR analysis indicated a 71% yield of a HEP propoxylate having an average of 25 propylene oxide adducts. The crude product was further purified by the procedure of Example 1 to give a final product having an estimated molecular weight of approximately 1600. GPC analysis indicated an average molecular weight of Mw=1260 and a polydispersity of 1.11.

Example 4

The procedure of Example 1 was repeated with the exception that the crude product was further purified using a filtration procedure. The crude product was mixed with disodium dihydrogen pyrophosphate (Na₂ H₂ P₂ O₇, 1.25 molar ratio to potassium) and water (5% wt basis of product). The mixture was heated to 80° C. for over one hour with agitation. The slurry was filtered to remove solid material and to obtain a light-colored liquid as the final product containing less than 30 ppm by weight potassium and sodium.

Example 5

The procedure of Example 1 was repeated with the following exceptions: a mixture of N-(2-hydroxyethyl)-pyrrolidinone (40 g, 0.31 moles) and potassium hydride (1.2 g) were mixed for over 30 minutes at ambient temperature. No toluene was used. The resulting liquid was added along with 1,2-epoxybutane (561 g, 7.8 moles) to the autoclave. The autoclave was sealed and purged of air and filled with nitrogen to 200 psi while still at ambient temperature. The mixture was heated slowly to 137° C. and maintained at this temperature for over 6 hours. During the process, a maximum autogenous pressure at 319 psi at 137° C. was observed. The pressure dropped to 271 psi at the end of the reaction.

The crude product was purified using an extraction procedure in which the crude product was dissolved in hexane (50% basis of product) before being extracted three times with a mixture of methanol/ethanol/water at a ratio of approximately 1:0.2:1. The product was then subjected to rotovap at 80° C. and 10 mm Hg to obtain a light-colored (yellow) transparent fluid. A final product having an estimated molecular weight of approximately 2000 was obtained. GPC analysis indicated an average molecular weight of Mw=1440 and a polydispersity of 1.09.

Example 6

The procedure of Example 1 was repeated with the following exceptions: a mixture of N-(2-hydroxyethyl)-pyrrolidinone (59.5 g, 0.46 moles) and potassium hydroxide (1.7 g in 1.7 g water) was utilized in the absence of toluene. The resulting mixture was added along with 1,2-epoxybutane (540 g, 7.5 moles) to the autoclave. The mixture was heated slowly to 118° C. and maintained at this temperature for over 7 hours. During the process, a maximum autogenous pressure at 125 psi at 120° C. was observed.

The crude product was purified by the procedure of Example 1 to give a final product having an estimated molecular weight of approximately 1300. GPC analysis indicated an average molecular weight of Mw=1060 and a polydispersity of 1.08.

Example 7

The procedure of Example 1 was repeated with the following exceptions: a mixture of N-(2-hydroxyethyl)-pyrrolidinone (97 g, 0.75 moles), potassium hydroxide (1.4 g) and toluene (50 g) was stirred at ambient temperature under nitrogen atmosphere until dissolved. The mixture was subjected to rotary evaporation under reduced pressure (10 mm Hg) and heat (80° C.) to remove water. The resulting liquid was added along with 1,2-epoxybutane (503 g, 7.0 moles) to the autoclave. The pressure was increased to 200 psi and while stirring, the mixture was heated slowly to between 137° C. and 140° C. and held at this temperature for over 7 hours. During the process, a maximum autogenous pressure at 370 psi was observed.

The crude product was purified by the procedure of Example 1 to give a final product having an estimated molecular weight of approximately 800. GPC analysis indicated an average molecular weight of Mw=746 and a polydispersity of 1.05.

Example 8

The procedure of Example 1 was repeated with the following exceptions: a mixture of 2-pyrrolidinone (32 g, 0.38 moles) and potassium t-butoxide (1.7 g) was utilized in the absence of toluene. The resulting material was added with 1,2-epoxybutane (568 g, 7.9 moles) to the autoclave. The mixture was heated slowly to a temperature from 137° C. to 141° C. for over 7 hours. A pressure of from about 370 psi to about 278 psi was recorded during this time. The final product had an estimated molecular weight of approximately 1600. GPC analysis indicated an average molecular weight of Mw=1240 and a polydispersity of 1.08.

Example 9

The procedure of Example 1 was repeated with the following exceptions: a mixture of ε-caprolactam (42.4 g, 0.375 moles), potassium hydroxide (1.9 g in 1.5 g water) and toluene (100 g) was utilized. This mixture was added along with 1,2-epoxybutane (558 g, 7.75 moles) to the autoclave. The mixture was slowly heated to from 118° C. to 119° C. under nitrogen pressure (73 psi to 123 psi) for over 6 hours. The crude product was purified by the procedure of Example 1 to give a final product having an estimated molecular weight of approximately 1600. GPC analysis indicted an average molecular weight of Mw=1230 and a polydispersity of 1.09.

Example 10

A mixture of N-(2-hydroxyethyl)-pyrrolidinone (HEP) (129 g, 1.0 moles) and potassium t-butoxide (0.5 g) was heated to approximately 80° C. under a reduced pressure of 10 mm Hg for 30 minutes. The mixture was placed in a one liter autoclave, and the air was replaced with nitrogen. The reactor contents were pressured to 30 psig of nitrogen and heated to 150° C. Ethylene oxide (EO)(132 g, 3.0 moles) was fed slowly at 60 psig to the mixture over a 45 minute period. After the ethylene oxide was added, the mixture was maintained at 150° C. for an additional 30 minutes to complete the reaction. The reaction was cooled to ambient temperature without neutralization and the ethoxylate adduct was isolated.

A portion of the ethoxylated adduct (52 g, 0.2 moles) was dissolved in butylene oxide (BO)(288 g, 4.0 moles) at 25° C. and added to the autoclave. The autoclave was sealed, purged of air and pressurized to 50 psig using nitrogen. The system was heated to 140° C., producing a total pressure of 140 psig and maintained at this temperature for 5 hours. The reaction mixture was cooled to 25° C. and the crude yellow product was rotovapped at 80° C. and 10 mm Hg to remove any light material. A total of 330 grams was isolated. The product was purified by aqueous extraction as described in Example 1. The product was of the general formula HEP(EO)₃ (BO)₂₀ H with an estimated molecular weight of approximately 1800.

Example 11

An ethoxylate adduct was produced according to the procedure of Example 10 using N-(2-hydroxyethyl)-pyrrolidinone (103.2 g, 0.8 moles), potassium-t-butoxide (0.7 g) and ethylene oxide (246.4 g, 5.6 moles). The product was isolated unneutralized.

A portion of this ethoxylated adduct (87.4 g, 0.2 moles) was reacted with butylene oxide (245 g, 3.4 moles) according to the procedure of Example 10. The product was isolated and purified by aqueous extraction as described in Example 1. The product was of the general formula HEP(EO)₇ (BO)₁₇ H with an estimated molecular weight of approximately 1800.

Example 12

A mixture of N-(2-hydroxyethyl)-pyrrolidinone (23.2 g, 0.18 moles), potassium butoxide (1.0 g) and propylene oxide (301 g, 5.19 moles) was placed in an autoclave and pressurized to 200 psig using nitrogen. The contents were allowed to react at 120° C. for 9 hours. The pressure decreased from 395 psig to 250 psig over the course of the reaction. The reaction mixture was cooled, and the yellow product purified by aqueous extraction as described in Example 1. The estimated molecular weight of the product was approximately 1800.

Example 13

A mixture of N-(2-hydroxyethyl)-pyrrolidinone (23.2 g, 0.18 moles), potassium t-butoxide (1.0 g), propylene oxide (136 g, 2.34 moles) and 2-ethylhexyl glycidyl ether (obtained from Aldrich Chemical Company, 167 g, 0.9 moles) were reacted according to the procedure of Example 1. The final product was also purified by aqueous extraction as described in Example 1. The estimated molecular weight of the product was approximately 1800.

Example 14

A mixture of N-(2-hydroxyethyl)-pyrrolidinone (21.9 g, 0.17 moles), potassium t-butoxide (1.0 g) and 2-ethylhexyl glycidyl ether (234 g, 1.53 moles) was reacted according to the procedure of Example 1. The final product was purified by aqueous extraction as described in Example 1 to obtain a product having an estimated molecular weight of approximately 1800.

Example 15

A mixture of N-(2-hydroxyethyl)-pyrrolidinone (21.9 g, 0.17 moles), potassium t-butoxide (1.0 g), butylene oxide (142 g, 1.97 moles) and 2-ethylhexyl glycidyl ether (142 g, 0.765 moles) were reacted according to the procedure of Example 1. The product was purified by aqueous extraction as described in Example 1 to obtain a product having an estimated molecular weight of approximately 1800.

Example 16

A mixture of N-(2-hydroxyethyl)-pyrrolidinone (23.2 g, 0.18 moles), potassium t-butoxide (1.0 g) and isopropyl glycidyl ether (obtained from Aldrich Chemical Company, 301 g, 2.58 moles) was reacted according to the procedure of Example 1. The product was purified by aqueous extraction as described in Example 1 to obtain a product having an estimated molecular weight of approximately 1800.

Example 17

600 g (0.375 moles) of the product of Example 1 was placed in a one liter, 3-necked round-bottomed flask equipped with a mechanical stirrer, temperature controller, Dean-stark trap and water condenser. Under nitrogen atmosphere, 2-ethylhexanoic acid (54 g, 0.375 moles) was added. While stirring under nitrogen flow, the mixture was heated to from about 130° C. to about 180° C. for over 10 hours. Some light boiling materials (13 ml) were removed through the trap. The resulting material (an esterification product) was further purified by extraction with water and rotovapped under 80° C., 10 mm Hg vacuum. GPC analysis indicated a similar molecular weight and distribution to the compound of Example 1 but with a slightly broader polydispersity (1.12 vs. 1.09).

Example 18

The procedure of Example 1 was repeated with the exception that 300 g (4.16 moles) of 1,2-epoxybutane was utilized to obtain a product having an estimated molecular weight of 1800.

TEST RESULTS

In each of the following tests, the base fuel utilized comprised either premium unleaded gasoline (PU) (90+ octane, R+M/2!) and/or regular unleaded gasoline (RU) (85-88 octane, R+M/2!). Those skilled in the art will recognize that fuels containing heavy catalytically cracked stocks, such as most regular fuels, are typically more difficult to additize in order to control deposits and effectuate octane requirement reduction and octane requirement increase control. The cyclic amide alkoxylate compounds utilized were prepared as indicated by Example number and were used at the concentration indicated in ppm by weight. The tests employed are described below and the results of the various tests are set forth in the tables below.

Intake Valve Deposit Tests

Engines from vehicles were installed in dynamometer cells in such a way as to simulate road operation using a cycle of idle, low speed and high speed components while carefully controlling specific operating parameters. Fuels with and without the compounds of Formula I were tested in a variety of engines having port fuel injection including, 2.3 L Fords, 2.3 L Oldsmobiles (Olds), 3.3 L Dodges, 3.1 L Chevrolets (Chev) and 2.7 L BMWs to determine the effectiveness of the instant compounds in reducing intake valve deposits ("L" refers to liter). Carbureted 0.359 L Honda generator engines were also utilized to determine the effectiveness of the instant compounds in reducing intake valve deposits.

Before each test, the engine was inspected, the induction system components were cleaned and new intake valves were weighed and installed. The oil was changed and new oil and fuel filters, gaskets and spark plugs were installed.

In all engines except the Honda, the tests were run in cycles consisting of idle, 35 mph and 65 mph for a period of 100 hours unless indicated otherwise. In the Honda engines, the tests were run in cycles consisting of a no load idle mode for one minute followed by a three minute mode with a load at 2200 rpm's for a period of 40 hours unless indicated otherwise. At the end of each test, the intake valves were removed and weighed.

                  TABLE 2                                                          ______________________________________                                         Intake Valve Deposits in Honda Generator Engines                               Compound          Conc. ppm     Average Deposit                                Example #  Fuel   by Weight     Weight, mg                                     ______________________________________                                         1          PU     200           10.5*                                          --         PU     0             25.1*                                          1          PU     200           16, 10                                         2          PU     200            5                                             3          PU     200           17                                             7          PU     200           23                                             9          PU     200           12                                             --         PU     0             39                                             6          PU     200           27                                             --         PU     0             83, 79                                         1          RU     200           39                                             1          RU     300           34                                             2          RU     290           34                                             --         RU     0             98                                             ______________________________________                                          *Indicates an average of five tests in three different Honda generator         engines.                                                                 

Results of these tests demonstrate that the compounds of the present invention are very useful in significantly preventing the accumulation of deposits on the intake valves in the generator engines tested as compared to the effects of the base fuel (indicated by no compound example # and 0 ppm by weight) as shown by the much lower average valve deposits.

                  TABLE 3                                                          ______________________________________                                         Intake Valve Deposits in Various Engines                                       Compound                  Conc. ppm                                                                              Average Deposit                              Example #                                                                              Engine    Fuel    by Weight                                                                              Weight, mg                                   ______________________________________                                         --      2.8 L Chev                                                                               PU      0       232*                                         1       "         PU      100     297                                          1       "         PU      200     212                                          1       "         PU      300     232                                          1       "         PU      400      55                                          --      2.3 L Olds                                                                               PU      0       174*                                         1       "         PU      200      56                                          1       "         PU      300      67                                          --      3.3 L Dodge                                                                              PU      0       211                                          1       "         PU      200     176                                          9       "         PU      200      28                                          4       "         PU      200     132                                          8       "         PU      200      77                                          9       "         PU      200      28                                          --      3.1 L Chev                                                                               PU      0        72                                          1       "         PU      200     38, 69                                       1       "         PU      300     115                                          9       "         PU      200      33                                          --      "         RU      0       143                                          1       "         RU      200     470                                          9       "         RU      200     235                                          --      2.7 L BMW PU      0       138*                                         1       "         PU      200      86                                          4       "         PU      200     123                                          5       "         PU      200     115                                          --      2.3 L Ford                                                                               PU      0       242                                          1       "         PU      200      59                                          2       "         PU      200     122                                          9       "         PU      200      50                                          --      "         RU      0       243                                          1       "         RU      200     193                                          9       "         RU      200     194                                          2       "         RU      200     242                                          17      "         RU      200     388                                          ______________________________________                                          *Indicates that base fuel having a different blend but the same octane wa      utilized.                                                                

Results of these tests demonstrate that the compounds of the present invention are very useful in significantly preventing the accumulation of deposits on the intake valves in the majority of the engines tested as compared to the effects of the base fuel (indicated by no compound example # and 0 ppm by weight) as shown by the lower average valve deposits.

                  TABLE 4                                                          ______________________________________                                         Intake Valve Deposit Tests Utilizing                                           Additional Detergents and Carrier Fluids                                       Additional intake valve deposit tests (as defined                              herinbefore) were conducted in the 2.7 L BMWi utilizing                        compounds as prepared in Example 1 and additional components                   (detergents or carrier fluids) in regular unleaded gasoline.                   Conc. ppm   Conc. ppm                                                          by Weight of                                                                               by Weight of  Average Deposit                                      Example 1   Additional Component                                                                         Weight, mg                                           ______________________________________                                         0           0             185                                                  200          50 ppm OGA-480.sup.1                                                                        219                                                  200          50 ppm PIB-DAP.sup.2                                                                        233                                                  125         125 ppm PIB-DAP.sup.2                                                                         32                                                  150         300 ppm PIB.sup.3                                                                            115                                                  150         300 ppm PAO.sup.5                                                                            189                                                  200         250 ppm PPO.sup.5                                                                            199                                                  125         125 ppm MA.sup.6                                                                              5                                                   ______________________________________                                          .sup.1 OGA480  a poly(oxyalkylene) carbamate available commercially from       Oronite.                                                                       .sup.2 PIBDAP  Npolyisobutenyl-N',Ndimethyl-1,3-diaminopropane, Mw = 1050      .sup.3 PIB  polyisobutylene, Mw = 750.                                         .sup.4 PAO (8 cst)  polyalpha olefins (8 cst).                                 .sup.5 PPO  Polypropylene oxide, MW = 1600.                                    .sup.6 MA  an alkyl substituted Mannich amine also known as Amoco 595,         commercially available from Ethyl Additives.                             

Results of these tests demonstrate that the compounds of the present invention, when combined with carrier fluids or additional detergents are useful in preventing the accumulation of deposits on intake valves.

                  TABLE 5                                                          ______________________________________                                         Intake Valve Deposit Tests Utilizing                                           Additional Detergents and Carrier Fluids                                       Additional intake valve deposit tests (as defined                              hereinbefore) were conducted in the 0.359 L Honda generator                    engine utilizing compounds as prepared in Example 1 and                        additional components (detergents or carrier fluids) in regular                unleaded gasoline.                                                             Conc. ppm                                                                               Conc. ppm                                                             by weight of                                                                            by weight of  Average Deposit                                                                            CC Dpst                                     Example 1                                                                               Additional Component                                                                         Weight, mg  Wt (mg)                                     ______________________________________                                         125      0             49.0        1133                                        125      125 ppm PIB-DAP.sup.1                                                                        0.4         1492                                        125      125 ppm MPDC.sup.2                                                                           29.3        1520                                        125      300 ppm EN-900.sup.3                                                                         29.4        --                                          ______________________________________                                          .sup.1 PIBDAP  Npolyisobutenyl-N',Ndimethyl-1,3-diaminopropane, Mw = 1050      .sup.2 MPDC  Methyl PibDap Carbamate, Mw = 1100.                               .sup.3 EN900  Exxon Naphthenic 900 sus.                                  

Results of these tests further demonstrate that the compounds of the present invention, when combined with carrier fluids or co-detergents are useful in preventing the accumulation of deposits on intake valves.

                                      TABLE 6                                      __________________________________________________________________________     Honda Generator Engine Test Results Using Various Alkylene Oxide Adducts       of HEP                                                                         Additional intake valve deposit tests (as defined hereinbefore) were           conducted in 0.359 L Honda generator engines                                   in premium unleaded gasoline using a variety of alkylene oxide adducts of      N-(2-hydroxyethyl)-pyrrolidinone (HEP). The various                            derivatives constitute variations of the polyether backbone in one of          three ways:                                                                    a) mixtures of ethylene oxide (EO)/butylene oxide (BO)                         b) mixtures of propylene oxide (PO)/other alkylene oxides                      c) other pure alkylene oxides.                                                 For purposes of clarity the hydrogens have been eliminated from the ring       structures of Table 6. Example 1 was                                           included for comparison. All compounds have an estimated molecular weight      of approximately 1800 and were used at 200 ppm                                 by weight concentrations.                                                      Compound                                                                             Chemical                                      Average                    Example                                                                              Description                                                                              Structure                           Deposit                    __________________________________________________________________________      18*  HEP(BO).sub.24 H                                                                          ##STR19##                          12.2                        10*  HEP(EO).sub.3 (BO).sub.20 H                                                               ##STR20##                          13.9                        11*  HEP(EO).sub.7 (BO).sub.17 H                                                               ##STR21##                          14.9                       12    HEP(PO).sub.29 H                                                                          ##STR22##                          18.7                       13    HEP(PO).sub.14 (EHGE).sub.5 H                                                             ##STR23##                          26.5                       18    HEP(BO).sub.24 H                                                                          ##STR24##                          7.9                        14    HEP(EHGE).sub.9 H                                                                         ##STR25##                          18.1                       15    HEP(BO).sub.11 (EHGE).sub.5 H                                                             ##STR26##                          12.6                       16    HEP(GIE).sub.14 H                                                                         ##STR27##                          22.6                       __________________________________________________________________________      *Indicates that a different Honda generator engine was used as compared t      those test runs without an asterisk.                                           The following abbreviations were used throughout Table 6:                      HEP = n(2-hydroxyethyl)-pyrrolidinone                                          BO = butylene oxide                                                            EO = ethylene oxide                                                            PO = propylene oxide                                                           EHGE = ethylhexyl glycidyl ether                                               GIE = glycidyl isopropyl ether                                                 The results of Table 6 show the importance of the variation of                 alkoxylation backbones.                                                  

METHOD FOR OCTANE REQUIREMENT REDUCTION AND OCTANE REQUIREMENT Increase Control

The purpose of octane requirement tests in engine dynamometer cells is to provide a method of determining the effect of various gasoline components and additives upon the octane requirement of the engine. Measurement of the effect of the induction system and combustion chamber deposits on octane requirement may also be performed.

Engines from vehicles are installed in dynamometer cells in such a way as to simulate road operation using a cycle of idle, low speed and high speed components while carefully controlling specific operating parameters. Two types of octane requirement test are conducted: octane requirement increase control and octane requirement reduction. Contribution of specific deposits to octane requirement may also be determined.

Prior to testing, each engine is inspected and has its induction system cleaned. Parts are checked for excessive wear and a new oil filter, fuel filter, intake valves and spark plugs are installed.

Octane requirement is measured initially with the clean engine, then at specific intervals, until a stable requirement is established. Test stand engines reach an octane stabilization in about 250 hours, or 9500 miles equivalent (168 hours per week). After stabilization, the engine is disassembled, cleaned, reassembled and the octane requirement measured again. This second clean engine octane requirement is referred to as "check back" since it checks back to the initial requirement. The check back octane requirement is the test reference, as it accommodates engine changes that occur throughout the test. A check back octane requirement significantly different from the initial requirement indicates a problem with the test. The difference between the check back octane requirement and the stable octane requirement is the octane requirement increase achieved during the test.

The entire process is repeated using the test gasoline. An octane requirement level established by the test gasoline less than the base gasoline represents octane requirement increase control favorable to the test gasoline.

Octane requirement reduction is a performance feature that demonstrates a reduction from the established octane requirement of a base gasoline in a given engine. The test need not start with a clean engine. The test protocol requires measurement of the octane requirement of an engine fueled with a base gasoline which generally consists of the test gasoline without additives or special treatment. However, the base gasoline may contain additives for a specific comparison. After reaching a stable octane requirement with the base gasoline, the engine is operated on test gasoline until the octane requirement again stabilizes. Rating intervals for test stands are typically twenty-four hours. Test stand engines may be used to conduct several octane requirement reduction tests in sequence with the engine being restabilized on base gasoline between each test. A stable reduction of octane requirement from that of the base gasoline represents octane requirement reduction favorable to the test gasoline.

                  TABLE 7                                                          ______________________________________                                         OCTANE REQUIREMENT INCREASE CONTROL TESTING                                    All tests were conducted using 200 ppm by weight of Example 1.                                     Base Fuel Octane Requirement                                                   Minus Test Fuel Octane                                     Test Engine  Fuel   Requirement*                                               ______________________________________                                         1989 3.8 L Buick                                                                            PU     5                                                          "            RU     1                                                          1990 3.1 L Chev                                                                             PU     3                                                          "            RU     1                                                          1991 3.3 L Dodge                                                                            PU     0                                                          1987 2.3 L Ford                                                                             PU     3                                                          1988 2.3 L Olds                                                                             PU     2                                                          ______________________________________                                          *Positive numbers indicate good octane control performance.              

The overall results indicate that the compound of Example 1 possesses the ability to control octane requirement increases relative to the base fuel in the majority of engines tested.

                  TABLE 8                                                          ______________________________________                                         OCTANE REQUIREMENT REDUCTION TESTING                                           All tests were conducted using 200 ppm by weight of                            the compound indicated.                                                                                     Base Fuel Octane                                  Compound                     Requirement Minus Test                            Example #                                                                             Test Engine Fuel      Fuel Octane Requirement*                          ______________________________________                                         1      1989 3.8 L Buick                                                                           RU        0                                                 1      "           PU        2                                                 1      1990 3.1 L Chev                                                                            PU        4                                                 1      "           PU plus   3                                                                    Deposit                                                                        Control                                                                        Package**                                                   1      "           RU        2                                                 1      1991 3.3 L Dodge                                                                           PU        -3                                                1      1987 2.3 L Ford                                                                            PU        3                                                 1      1988 2.3 L Olds                                                                            PU        3                                                 9      1990 3.1 L Chev                                                                            PU        3                                                 ______________________________________                                          *Positive numbers indicate good octane requirement reduction performance.      **The base fuel contains an additive package comprising a PIB amine and a      synthetic carrier for comparative purposes.                              

The overall results indicate that the compound of Example 1 possesses the ability to reduce octane requirement relative to the base fuel in the majority of the engines tested. Limited engine tests utilizing Example 9 also show a tendency for octane requirement reduction.

Induction System Deposit Test

The induction system deposit test is a measure of detergency performance in the manifold/valve/port area of an engine induction system. The test involves spraying a mixture of test gasoline and lubricating oil on a hot aluminum tube. The test measures the tendency of the additive package to disperse the carbonaceous deposit generated on the tube. The clean area at the center of the deposit ring on the tube is measured. Generally, the more the deposit is dispersed, the better the manifold/valve/port detergency performance of the gasoline or additive tested. Experience has shown that gasolines giving above about 200 square millimeters clean area provide good intake valve detergency performance, while those giving below about 120 square millimeters are not effective inlet valve detergents. Base fuels give zero clean area. The test conditions are as follows:

    ______________________________________                                         Spray Nozzle Air Pressure:                                                                             8 psi                                                  Air Flow:               12 1/min                                               Nitrogen Pressure on Test Fuel:                                                                        4.8 psi                                                Test Fuel Volume:       100 cc                                                 Test Fuel Flow:         2 cc/min                                               Aluminum Tube Temperature:                                                                             260° C. ± 3° C.                       Oil, Shell Fire & Ice.sup.™ 10W/40:                                                                 0.2 cc/100 cc Fuel                                     ______________________________________                                    

                  TABLE 9                                                          ______________________________________                                         Compound      Concentration                                                                             Clean Area                                            Example #     ppm by Weight                                                                             Sq. mm                                                ______________________________________                                         --            0          0                                                     3             200 ppm    38                                                    1             200 ppm    209                                                   ______________________________________                                    

A significantly better dispersity is demonstrated utilizing the compound of Example 1 when compared to the compound of Example 3. This demonstrates the importance of structure in determining deposits.

BMW TESTS

10,000 Mile tests to determine intake valve deposits were conducted in 1985 BMW 318i cars having in-line, four cylinder, 4-stroke, water cooled gasoline engines that have a single overhead camshaft, two valves per cylinder and a displacement of 1.8 liters. The engines were port fuel injected equipped with Bosch port fuel-injectors and L-Jetronic fuel management systems. All cars used were equipped with overdrive automatic transmissions.

Before the test started, all combustion chamber deposits were removed from the engine head, intake manifold and piston tops. New intake valves were weighed and installed. The oil and filters were changed, new spark plugs were installed and the fuel injectors flow checked. Mileage was accumulated on public roads using trained drivers. The test route consisted of about 10% city driving (varied speeds with stop-and-go idling), 20% on secondary roads (moderate speeds with infrequent stops) and 70% highway driving (maximum speed of 65 mph).

The primary test data was the intake valve deposits weights at the end of the 10,000 mile test. BMW's pass criteria are as follows: an average deposit weight of 100 milligrams/valve or less at the conclusion of the 10,000 mile test meets BMW requirements for unlimited mileage acceptance; an average deposit weight of 250 mg/valve or less at the conclusion of the test meets BMW's requirement for 50,000 mile service.

    __________________________________________________________________________     BMW 318i Test Results                                                          Compound                                                                             Concentration                                                                         Additional                                                                           Concentration                                                                            Average Deposit wt.                               Example #                                                                            ppm by wt.                                                                            Detergent                                                                            ppm by wt.                                                                            Fuel                                                                              at miles × 1000                             __________________________________________________________________________     1     200    --    --     PU 37  mg at 10                                      1     200    --    --     RU 111 mg at 5                                       1     300    --    --     RU 254 mg at 5                                       1     200    PPO.sup.1                                                                            125    RU 152 mg at 5                                       1     200    PIB.sup.2                                                                            300    RU 128 mg at 5                                       1     160    PIB--DAP.sup.3                                                                       90     RU 42  mg at 5                                       1     160    PIB--DAP.sup.3                                                                       90     RU 65  mg at 10                                      1     200    PPO.sup.1                                                                            250    RU 87  mg at 5                                       1     125    PIB--DAP.sup.3                                                                       125    RU 1.4 mg at 5                                       1     125    PIB--DAP.sup.3                                                                       125    RU 51  mg at 10                                      1     125    PBO.sup.4                                                                            200    RU 100 mg at 5                                       1     200    PIB--DAP.sup.3                                                                       50     RU 326 mg at 5                                       1     150    OGA-480.sup.5                                                                        100    RU 131 mg at 5                                       1     200    PIB--DAP.sup.3                                                                       75     RU 91  mg at 10                                      __________________________________________________________________________      .sup.1 PPO = polypropylene oxide, Mw = 1600.                                   .sup.2 PIB = polyisobutylene, Mw = 750.                                        .sup.3 PIB--DAP = Npolyisobutenyl-N',N'-dimethyl-1,3-diaminopropane, Mw =      1050.                                                                          .sup.4 PBO = poly(butylene)oxide, Mw = 1450.                                   .sup.5 OGA480 = a poly(oxyalkylene)carbamate available commercially from       Oronite.                                                                       The results of Table 10 demonstrate the advantages of using the compounds      of the present invention alone and in formulations with other existing         detergents and carrier fluids.                                            

What is claimed is:
 1. A compound having the formula: ##STR28## wherein x is from 2 to 4; y is from 1 to 50; R₁ and R₂ are independently hydrogen or hydrocarbyl of 1 to 100 carbon atoms; R₃ is hydrocarbyl of 1 to 100 carbon atoms; R₄ is hydrocarbyl of 2 to 100 carbon atoms with the proviso that when y is greater than 1, each R₄ may be the same or different but at least R₃ or one R₄ must be hydrocarbyl of at least four carbon atoms; and R₅ is hydrogen, hydrocarbyl of 1 to 100 carbon atoms or acyl of 1 to 20 carbon atoms.
 2. The compound of claim 1 wherein R₄ is hydrocarbyl of the formula: ##STR29## wherein R₈ is independently hydrogen or hydrocarbyl of 1 to 20 carbon atoms and R₆ is independently hydrogen or hydrocarbyl of 1 to 20 carbon atoms.
 3. The compound of claim 2 wherein x is
 3. 4. The compound of claim 3 wherein R₁ and R₂ are hydrogen; y is from 10 to 40; and R₃ is hydrocarbyl comprising alkyl of 1 to 20 carbon atoms.
 5. The compound of claim 4 wherein R₃ is hydrocarbyl comprising alkyl of 2 carbon atoms.
 6. The compound of claim 5 wherein R₆ is independently hydrogen or hydrocarbyl comprising alkyl of 1 to 12 carbon atoms and R₅ is hydrogen.
 7. The compound of claim 6 wherein R₆ is independently hydrogen, hydrocarbyl comprising alkyl of 1 to 2 carbon atoms or hydrocarbyl comprising oxy-substituted alkyl of 1 to 12 carbon atoms and R₅ is hydrogen. 